Polling slows down bandwidth

Paul Thornton prt at prt.org
Sat Oct 30 11:32:23 UTC 2010


On 29/10/2010 18:23, Chuck Swiger wrote:
> On Oct 28, 2010, at 11:39 PM, Коньков Евгений wrote:
>> so using polling on gigabit NICs is a bottle neck? and is cause of low performance, is not?
> Simple answer is yes.  It should be possible that you could tune polling to get similar performance, or at least better performance than you see now, but the additional hardware capabilities of gigabit NICs are likely to outperform polling mode, just as polling mode can generally outperform old 100MBs ethernet NICs.

I have been using polling for a long time with em and fxp interfaces on
6.2 and 4.9 boxes that are working as routers.

I've been doing testing with FreeBSD 8 and em interfaces recently, and
my experience agrees with Chuck's statement - that polling makes things
worse when you use new (anything in the last 2 or 3 years) hardware with
good quality gigabit ethernet interfaces.

I've only really worked with bge and em but they have good high
performance without polling in 8.0 and 8.1


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